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Abstract:

A system and method are disclosed for automatically limiting the drainage
of a bodily fluid such as cerebrospinal fluid (CSF) from a patient into a
collection chamber. The collection chamber includes a vent having an
hydrophobic filter for the passage of air to facilitate the movement of
CSF yet to maintain a closed system. The system includes a buoyant float
hingedly connected with the top of the collection chamber in one
embodiment. When fluid rises in the collection chamber to a predetermined
volume, buoyant force raises the float and causes a seal plug mounted on
top of the float to seal one of an inflow port or a vent port. The float
is limited to pivoting movement in one plane and to a certain angle
within that plane. The system and method avoid overdrainage of CSF from
the patient and overfilling of the collection chamber.

Claims:

1-17. (canceled)

18. A method of controlling the flow of bodily fluid comprising the steps
of: receiving the bodily fluid in a fluid collection chamber through an
inflow port disposed in a top member of the chamber, the chamber also
having a bottom member and a side wall interconnecting the top member
with the bottom member, the collection chamber also comprising a first
hinge component formed at a fixed position on at least one of the top
member and the side wall, the inflow port including a first valve
component with which the inflow port may be configured to an open
configuration at which fluid flows into the collection chamber through
the inflow port and a closed configuration at which fluid is blocked from
flowing into the collection chamber through the inflow port; accumulating
the received bodily fluid in the collection chamber to form a fluid
surface in the chamber that rises as the bodily fluid is accumulated and
that develops a buoyant force; venting the collection chamber to
atmospheric pressure through a vent port; applying the buoyant force to a
buoyant float member disposed within the collection chamber below the
inflow port, the float member being hingedly mounted to the collection
chamber by means of a hinge arm with a float member chamber disposed at a
first end of the hinge arm and a second hinge component located at a
second opposing end of the hinge arm, the second hinge component being
pivotally connected with the first hinge component of the fluid
collection chamber to form a mounting hinge; moving the float member
upwards in a pivoting motion about the mounting hinge toward the top
member of the collection chamber according to the amount of fluid in the
fluid collection chamber, as a result of the buoyant force; and
controlling the flow of bodily fluid through the inflow port into the
collection chamber with a second valve component located on the float
member chamber adjacent the first end of the hinge arm, the second valve
component configured to interact with the first valve component of the
inflow port such that when the float member chamber moves pivotally
downward, the second valve component and first valve component interact
to place the inflow port in the open configuration, and such that when
the float member chamber is in an open configuration thereby leaving the
inflow port open, and moves pivotally upward into a closed configuration
in response to buoyant force of bodily fluid filling the chamber, the
second valve component and first valve component interact to place the
inflow port in the closed configuration closing the inflow port when the
bodily fluid in the collection chamber reaches a predetermined level,
thereby blocking the inflow of bodily fluid into the collection chamber
with the float member upon accumulating a predetermined volume of bodily
fluid in the chamber.

19. (canceled)

20. The method of claim 18 wherein the step of blocking the inflow
comprises sealing the inflow port with a plug mounted to the float
member, the plug having an apex disposed so that it is always within the
inflow port whether the collection chamber is empty or is full.

21. The method of claim 18 further comprising the step of limiting
torsional movement of the float member so that movement of the float
member is substantially confined to pivoting movement in one plane.

22. The method of claim 18 further comprising limiting pivotal movement
of the float member to a predetermined angle.

23. The method of claim 19 wherein the step of blocking the inflow of
bodily fluid comprises sealing the vent port with a plug mounted to the
float member, the plug having an apex disposed so that it is always
within the vent port whether the collection chamber is empty or is full.

24-36. (canceled)

Description:

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to medical drainage systems
configured to remove bodily fluids from a patient, and more particularly,
to a medical drainage system to controllably remove bodily fluids, such
as cerebrospinal fluid (CSF), from a patient.

[0003] 2. Brief Description of Related Art

[0004] Cerebrospinal fluid (CSF) is normally a clear watery body fluid
that is formed by the human body in the ventricular cavities located
within the brain. The CSF flows from the lateral ventricles and third
ventricle to the fourth ventricle. Thereafter, the CSF under normal
conditions exits the fourth ventricle to flow into the subarachnoid
spaces that surround the outside of the brain, the spinal cord, and the
lumbosacral nerve roots. The CSF under normal conditions forms at a rate
of about 400-500 milliliters per day and is absorbed by the body at the
exact same rate, such that the equilibrium between the formation of CSF
and the absorption of CSF exists. This balance between the formation of
CSF and the absorption of CSF prevents CSF from accumulating under
pressure in the central nervous system. A rise in intracranial pressure
(ICP) from the accumulation of excess amounts of CSF may lead to
headaches, coma, or even death.

[0005] Accumulation of CSF above normal physiological levels may occur for
a variety of reasons. Blockage of the flow of CSF may cause accumulation
of CSF in the ventricles and a rise in ICP. Such blockages to the flow of
CSF may result from tumors or may be associated with subarachnoid
hemorrhage, for example when an intracranial aneurysm ruptures. Increased
intracranial pressures may also occur in pseudotumor cerebri; a condition
where more CSF is formed than is absorbed. Furthermore, increased ICP may
be associated with infections such as meningitis.

[0006] External CSF drainage systems are typically used in a clinical
setting when it is desirable to drain CSF through a catheter and into a
"closed" collection system to prevent infection of the CSF that may
result in meningitis. CSF drainage is desirable in the treatment of
patients having increased intracranial pressure (ICP), a condition where
the pressure of CSF or brain matter in the skull exceeds the normal upper
physiological limits of pressure. External CSF drainage is also desirable
to lower increased or normal ICP in patients with pathological CSF
leakage from the nose (rhinorhea) or ears (otorhea) such as may occur
with fractures of the base of the skull. Lowering the ICP frequently
allows the fractures to heal and the leak to seal without more aggressive
surgical intervention. External CSF drainage is also used in patients
with hydrocephalus, a condition where CSF pathologically accumulates in
the ventricles of the brain. Furthermore, external CSF drainage is used
for temporary drainage when an internalized CSF shunt system fails or is
infected.

[0007] Some conditions causing increased ICP may be treated by drainage of
CSF. Surgical drainage of CSF may be performed by either a ventricular
catheter, which is inserted into a lateral ventricle of a cerebral
hemisphere, or by a lumbar drainage catheter, which is inserted into the
subarachnoid space in the lumbar spine. These catheters allow for removal
of excess CSF.

[0008] Removal of too much CSF, or "overdrainage," by these catheters is
also not desirable. Excessive CSF drainage by ventricular or lumbar
catheters may result in severe headaches or collapse of the ventricular
cavities. Collapse of the ventricular cavities may cause movement of the
cerebral cortex inwardly, sometimes causing traction on veins that
rupture and form subdural hematomas. Excessive collapse of the ventricles
may also cause shifts of the brain and cerebral arteries, thereby causing
re-rupture of an intracranial aneurysm. Measured drainage of the CSF
through ventricular or lumbar drainage catheters is highly desirable.
Furthermore, drainage of CSF through these catheters is preferably done
in a closed system, for example a sealed bag, wherein the CSF has very
limited exposure to microbes in room air. CSF is typically sterile when
drained from the patient and contamination of the CSF by microbes may
have adverse consequences on the patient.

[0009] Several drainage systems configured for the generally closed
drainage of CSF from either the lumbar subarachnoid space or cerebral
ventricles have been described. These drainage systems typically include
tubing and one or more valves such as stopcocks to control the flow of
CSF from the patient through the drainage catheter. These drainage
systems also typically include a sterile bag or other type of container
for collection of the CSF.

[0010] Clinicians generally wish to limit CSF drainage from the patient to
a rate of about 10 milliliters to 50 milliliters per hour so that
overdrainage does not occur. Overdrainage of CSF from the patient can
result in "overfilling" of the drainage bag which is a condition wherein
too much CSF fluid fills the drainage bag. Overfilling a drainage bag or
container may cause further problems, including leakage of the fluid from
the system and infection through the pathway provided by the leaking
fluid.

[0011] Overfilling may also cause undesirable CSF contact with portions of
a drainage system that function best when kept dry, for example an
hydrophobic filter. In certain containers, such as a rigid-wall burette,
a vent is required for filling the container and then also for draining
the container. To maintain a closed system, a filter is typically located
at the vent so that air may leave as the container is being filled and
filtered air may enter as the container is being emptied. The vent filter
is typically hydrophobic so that liquid within the container does not
escape to the environment and liquid outside the container does not enter
the container. The filter may also include an anti-microbial substance or
it may antimicrobial due to the filter media pore size. Pore size less
than three microns is considered to be antimicrobial as bacteria cannot
pass through this aperture. CSF typically includes glucose and other
proteinaceous substances and should CSF come into contact with a vent
filter, it may adhere to the filter thereby making the passage of air
through the filter in either direction difficult or impossible. The
container would then be rendered useless and must be replaced. Therefore,
in the case where a collection container having a vent filter is used for
collecting CSF, it would be desirable to limit the amount of CSF flowing
into the collection container so that the CSF does not contact the vent
filter. Controlling the amount of CSF entering a container has been done
in the past by clinicians closely visually monitoring the level of CSF in
the container and when the amount reaches a certain level, closing a
stopcock to prevent such complications from overdrainage and overfilling.
Such monitoring requires the personal attention and time from clinicians
who are probably already quite busy.

[0012] The flow rate of CSF in many drainage and collection systems is
crudely controlled by the level at which the collection system is
positioned above the head or spine of the patient being treated. Flow may
unexpectedly increase if the level of the system is lowered in relation
to the level of the catheter entering the patient. For example, an
uncooperative or confused patient may sit up in bed, thereby changing his
position farther above where the system has been positioned and result in
an increased flow rate of CSF into the drainage and collection system.
These systems may further result in overdrainage when the collection
container is inadvertently positioned too low and/or drainage goes
unnoticed by the busy clinician for some time. A more serious risk can
occur when a displaced collection container falls or is compressed
thereby forcing a large volume of the collected CSF back into the
patient. Flow of CSF through a drain may also suddenly increase with
coughing or sneezing by the patient. Excess drainage may also occur from
siphoning phenomenon. Overfilling may occur if a busy clinician does not
empty the collection chamber of CSF before it fills to undesirable
levels. Therefore with these present systems, the amount of CSF flowing
out of the patient must be closely monitored by a clinician to prevent
complications from overdrainage and overfilling.

[0013] Medical drainage systems have been described in the art that
include various types of flow or pressure regulating valve systems. The
systems sometimes also include a vent system or antisiphoning mechanism.
One device known in the art is an external ventricular drainage assembly
that includes a ventricular drainage catheter placed in the ventricles of
a patient's brain and which is connected to a suture tab for securing the
catheter to the patient for preventing relative movement between the
catheter and patient. A manually operated valve such as a stopcock is
connected to the catheter for selectively opening and closing the
external ventricular drainage assembly to fluid flow. An adapter is
connected to the stopcock valve for providing access to the fluid flow
path within the assembly. A one-way valve such as a miter valve having no
moving parts is connected to the adapter. A first length of flexible
tubing is connected to the one-way valve and is joined through a
connector to a second length of flexible tubing. A collection reservoir
is connected to the second length of flexible tubing and includes an
entry and outlet port. A drip chamber is positioned between the second
length of flexible tubing and the collection reservoir. This is a
manually-controlled system as described above.

[0014] Another known device is a ventricular drainage system that includes
an antisiphon device having a chamber configured for vertical inflow of
CSF from the bottom of the chamber to the top of the chamber. An outflow
tube is connected at the upper end of the chamber. The device also
includes a freely floating ball in the chamber that is capable of closing
the inflow tract at the bottom of the chamber when there is no flow of
fluid from the ventricular catheter, capable of allowing fluid flow
through the chamber during a normal flow of liquid from the catheter and
capable of closing the outflow tract upon a rush of fluid from the
catheter. Such a system does not account for overfilling.

[0015] Also known in the art is a drainage system having an in-line
one-way valve for use in the drainage of ventricles of a patient's brain
or of the patient's lumbar region and which is connected to a catheter
inserted in either the ventricles or lumbar region and secured to the
patient. The system includes tubing from the catheter, a four-way
stopcock inserted into the tubing followed by a Y-connector providing a
sampling site, and a low-pressure one-way valve in line with the tubing
to help prevent reflux of fluid into the ventricles or lumbar
subarachnoid space. A length of flexible tubing leads from the one-way
valve to a burette clamped onto an IV pole, and a drainage bag connected
to the bottom of said burette to receive the collected fluid from the
burette after it is measured. This system also does not prevent
overfilling and requires manual monitoring.

[0016] The above devices known in the art all have disadvantages when
applied to clinical use for measured CSF drainage. For example, prior art
devices do not provide an automatic limitation of flow, or they are
complicated and expensive to manufacture, fill from the bottom, clog
easily when exposed to proteinaceous fluids, or may hamper the free flow
of CSF between a patient and a collection container.

[0017] Hence those skilled in the art have recognized a need for a
drainage system that avoids conditions of both overdrainage and
overfilling. What is needed is a system and method that limit the volume
of CSF draining into a collection device such that the volume of drained
CSF can be controlled, accurately measured, and configured so that a
drainage collection container can be conveniently removed from the bottom
of the collection chamber as required. A need also exists for a CSF
drainage device that is inexpensive and disposable. There is a further
recognized need for a CSF device that provides automatic shut off of
fluid flow at a predetermined volume of drainage and which prevents
overfilling so as to prevent CSF from coming into contact with a vent
filter. The present invention provides solutions to these and other
identified needs in the art.

SUMMARY OF THE INVENTION

[0018] Briefly and in general terms, the present invention is directed to
a system and method for automatically limiting the volume of bodily fluid
drained into a collection device. In accordance with aspects of the
invention, there is provided a bodily fluid drainage system, comprising a
fluid collection chamber formed by a top member connected to a bottom
member by a side wall, an inflow port disposed in the top member and
configured for receiving bodily fluid into the collection chamber, a vent
port disposed in the top member, and a buoyant float member disposed in
the collection chamber below the inflow port and pivotably connected with
the fluid collection chamber by a hinge such that the float member moves
pivotally downward in an open configuration leaving the inflow port open
when there is no bodily fluid in the chamber and moves pivotally upward
into a closed configuration in response to buoyant force of bodily fluid
filling the chamber closing the inflow port when the bodily fluid in the
chamber reaches a predetermined level.

[0019] In accordance with further aspects, the bodily fluid drainage
system further comprises a seal plug mounted on the float member below
the inflow port and moving with the float member, located so as to allow
flow of bodily fluid through the inflow port into the collection chamber
in the open configuration when the chamber has no fluid in it and closes
the inflow port so as to prevent the flow of bodily fluid through the
inflow port into the collection chamber in the closed configuration when
a predetermined volume of bodily fluid collects in the collection
chamber.

[0020] In a more detailed aspect, the seal plug has a conical shape, a
diameter of which is larger than an opening of the inflow port to
completely block the inflow port when in the closed configuration to
prevent the flow of bodily fluid into the chamber. The conical shape of
the seal plug includes an apex, the float member and seal plug disposed
in the chamber so that the apex is within the inflow port when in the
open configuration and also when in the closed configuration.

[0021] Further aspects in accordance with the invention comprise the float
member including a top portion at which is disposed a hollow chimney
extension having a pressure equalization hole at a top surface, the
pressure equalization hole configured to communicate with an interior of
the float member to equalize interior pressure with outside pressure
wherein a length of the hollow chimney extension is selected to place the
equalization hole high up in the collection chamber above the collected
fluid level thereby preventing the collected fluid from entering the
float member lumen under normal operating conditions. The pressure
equalization hole has a diameter that is selected to be small in size so
that it inhibits the movement of the bodily fluid through the
equalization hole to thereby avoid changes in buoyancy of the float
member.

[0022] Additional more detailed aspects include a seal plug mounted on a
top portion of the float member below the inflow port and moving with the
float member, and located so as to allow flow of bodily fluid through the
inflow port into the collection chamber in the open configuration when
the chamber has no fluid in it and closes the inflow port so as to
prevent the flow of bodily fluid through the inflow port into the
collection chamber in the closed configuration when a predetermined
volume of bodily fluid collects in the collection chamber, wherein the
seal plug is positioned on the float member between the chimney extension
and the hinge. In another aspect, the seal plug is positioned adjacent
the hinge.

[0023] In yet more detailed aspects, the hinge includes a hinge arm having
a width disposed on the float member two hinge pins located on either
side of the hinge arm, wherein the width of the hinge arm and locations
of the pins are selected to provide torsional stability to the float
member, and two hinge pin receiving members disposed on the fluid
collection chamber for receiving the two hinge pins to thereby pivotally
mount the float member. In a more detailed aspect, the hinge pin
receiving members are located on the top member. In another aspect, the
float member is configured so that its pivotal movement is limited to a
predetermined angle. In more detailed aspects regarding the float
configuration, the side wall has an inner surface having an inner
diameter, and the float member has a bottom portion having an outer
diameter that is smaller than the inner diameter of the side wall by a
predetermined distance such that pivotal movement of the hinged float
member in the direction of the open configuration is limited to the
predetermined angle by contact of the bottom portion of the float member
with the inner surface of the side wall.

[0024] Yet further detailed aspects include a filter connected to the vent
port. The filter in one aspect is configured to be hydrophobic. The
filter in another aspect is configured to be antimicrobial. The side wall
of the fluid collection chamber is transparent so that contents of the
collection chamber can be seen directly through the side wall. The side
wall of the fluid collection chamber includes volume markings. The top
member in another aspect also includes a vent chamber in connection with
the vent port and within which is disposed a vent filter. In certain
aspects, the vent filter may be hydrophobic and/or microbial.

[0025] In accordance with a volume-limited cerebrospinal fluid (CSF)
drainage system, there is provided a CSF collection chamber formed by a
top member connected to a bottom member by a side wall, an inflow port
disposed in the top member and configured for receiving CSF into the
collection chamber, a vent port disposed in the top member, a vent
chamber including an hydrophobic filter connected with the vent port, a
buoyant float member having a top portion and a bottom portion disposed
in the collection chamber below the inflow port, the float top portion
being pivotably connected with the top member of the chamber by a hinge
such that the float member moves pivotally downward to an open
configuration leaving the inflow port open when there is no CSF in the
chamber and moves pivotally upward to a closed configuration in response
to buoyant force of CSF flowing into the chamber closing the inflow port
when the CSF in the chamber reaches a predetermined level, and a seal
plug mounted on the top portion of the float member below the inflow port
and moving with the float member so as to allow flow of CSF through the
inflow port into the collection chamber in the open configuration and
moving with the float member so as to prevent the flow of CSF through the
inflow port into the collection chamber in the closed configuration when
a predetermined volume of CSF collects in the collection chamber, wherein
the seal plug has a conical shape, a diameter of which is larger than an
opening of the inflow port to completely block the inflow port when in
the closed configuration to prevent the flow of CSF into the chamber, the
top portion of the float member includes a hollow chimney extension
having a pressure equalization hole at a top surface, the pressure
equalization hole configured to communicate with an interior of the float
member to equalize interior pressure with outside pressure, wherein a
length of the hollow chimney extension is selected to place the
equalization hole high up in the collection chamber above the collected
CSF level thereby preventing the collected CSF from entering the float
member lumen under normal operating conditions, wherein the pressure
equalization hole has a diameter that is selected to be small in size so
that it inhibits the movement of CSF through the equalization hole to
thereby avoid changes in buoyancy of the float member, wherein the seal
plug is positioned on the float member between the chimney extension and
the hinge and adjacent the hinge; and wherein the wall of the fluid
collection chamber is transparent so that contents of the collection
chamber can be seen directly through the wall.

[0026] In accordance with aspects of a method in accordance with the
invention, there is provided a method of controlling the flow of bodily
fluid comprising the steps of receiving the bodily fluid in a collection
chamber through an inflow port disposed in a top of the chamber,
accumulating the received bodily fluid in the chamber to form a fluid
surface in the chamber that rises as the bodily fluid is accumulated and
that develops a buoyant force, applying the buoyant force to a float
member disposed within the collection chamber that is hingedly mounted,
moving the float member upwards in a pivoting motion about the mounting
hinge toward the top of the chamber as a result of the buoyant force, and
blocking the inflow of further bodily fluid with the float member upon
accumulating a predetermined volume of bodily fluid in the chamber.

[0027] In further detailed aspects, the method further comprises the step
of venting the collection chamber through a vent port so that air within
the chamber is vented to outside atmosphere during the step of
accumulating the received bodily fluid. The step of venting further
comprises preventing the passage of liquid during the venting step. The
step of venting also includes forcing vented air into contact with an
anti-microbial agent. The step of blocking the inflow comprises sealing
the inflow port or vent port with a seal plug mounted to the float
member. In another detailed aspect, the seal plug has an apex disposed so
that it is always within the inflow port whether the collection chamber
is empty or is full.

[0028] The method further comprises the step of limiting torsional
movement of the float member so that movement of the float member is
substantially confined to pivoting movement in one plane. The method
further comprises limiting pivotal movement of the float member to a
predetermined angle.

[0029] In another aspect in accordance with the invention, there is
provided a bodily fluid drainage system, comprising a fluid collection
chamber formed by a top member connected to a bottom member by a side
wall, an inflow port disposed in the top member and configured for
receiving bodily fluid into the collection chamber, a first vent port
disposed in the top member, and a buoyant float member disposed in the
collection chamber below the top member and pivotably connected with the
fluid connection chamber by a hinge such that the float member moves
pivotally downward in an open configuration leaving at least one of the
inflow port or the first vent port open and moves pivotally upward in a
closed configuration in response to buoyant force of bodily fluid filling
the chamber closing at least one of the inflow port or the vent port when
the bodily fluid in the chamber reaches a predetermined level. In another
feature, the bodily fluid drainage system further comprises a second vent
port disposed in the top member configured to permit air to flow into the
collection chamber.

[0030] In accordance with more detailed aspects, the bodily fluid drainage
system further comprises a one-way valve mounted in the second vent port
to permit air to flow into the collection chamber through the second vent
port but to prevent air from flowing out of the chamber through the
second vent port and wherein the buoyant float member is further
configured to move pivotally downward in an open configuration leaving
the first vent port open and to move pivotally upward in a closed
configuration in response to buoyant force of bodily fluid flowing into
the chamber closing the first vent port when the bodily fluid in the
chamber reaches a predetermined level. The bodily fluid drainage system
further comprises an outlet port located at the bottom member through
which fluid may flow out of the collection chamber wherein the one-way
valve has a cracking pressure that is selected to be approximately equal
to a pressure differential created within the collection chamber by fluid
flowing out through the outlet port.

[0031] In more detailed aspects, the inlet port is located in the top
member at a position opposite the hinge position and wherein the
collection chamber has an inner diameter and the buoyant float member has
an outer diameter that is selected to be smaller than the inner diameter
such that the buoyant member is not located under the inlet port in
either the open or closed configurations. Furthermore, the side wall of
the fluid collection chamber is transparent so that the flow of bodily
fluid into the collection chamber through the inflow port can be seen
directly through the side wall.

[0032] In other more detailed aspects, the bodily fluid drainage system
comprises a seal plug mounted on the float member below the first vent
port and moving with the float member, the seal plug being located so as
to allow air to flow out of the first vent port from the collection
chamber in the open configuration when the chamber has no fluid in it and
closes the first vent port so as to prevent the flow of air out of the
collection chamber in the closed configuration when a predetermined
volume of bodily fluid collects in the collection chamber.

[0033] In a more detailed aspect, the seal plug has a conical shape, the
diameter of which is larger than an opening of the first vent port to
completely block the first vent port when in the closed configuration to
prevent the flow of air out of the chamber. The conical shape of the seal
plug includes an apex, the float member and seal plug disposed in the
chamber so that the apex is within the first vent port when in the open
configuration and also when in the closed configuration.

[0034] In yet other aspects, the float member includes a top portion at
which is disposed a hollow chimney extension having a pressure
equalization hole at a top surface, the pressure equalization hole
configured to communicate with an interior of the float member to
equalize interior pressure with outside pressure wherein a length of the
hollow chimney extension is selected to place the equalization hole high
up in the collection chamber above the collected fluid level thereby
preventing the collected fluid from entering the float member lumen under
normal operating conditions. The bodily fluid drainage system wherein the
hinge includes a hinge arm having a width disposed on the float member,
two hinge pins located on either side of the hinge arm, wherein the width
of the hinge arm and locations of the pins are selected to provide
torsional stability to the float member, and two hinge pin receiving
members disposed on the collection chamber for receiving the two hinge
pins to thereby pivotally mount the float member to the top member. In a
more detailed aspect, the hinge pin receiving members are mounted to the
top member.

[0035] In yet further more detailed aspects, the float member is
configured so that its pivotal movement is limited to a predetermined
angle. The side wall has an inner surface having an inner diameter, and
the float member has a bottom portion having an outer diameter that is
smaller than the inner diameter of the side wall by a predetermined
distance such that pivotal movement of the hinged float member in the
direction of the open configuration is limited to the predetermined angle
by contact of the bottom portion of the float member with the inner
surface of the side wall.

[0036] The features and advantages of the invention will be more readily
understood from the following detailed description which should be read
in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 illustrates one embodiment of a volume limiting
cerebrospinal fluid drainage system wherein the system includes a lumbar
drainage catheter positioned in a patient to be treated, a bodily fluid
collection chamber, and a drainage bag with control valves or stopcocks
position along the fluid passage for manual control over drainage;

[0038] FIG. 2 is a frontal plan view of a portion of the volume limiting
cerebrospinal fluid drainage system of FIG. 1 showing a vented bodily
fluid collection chamber and the top of a drainage bag with a stopcock
position between the two to manually control the flow of fluid;

[0039] FIG. 3 is a right-side plan view of the portion of the volume
limiting cerebrospinal fluid drainage system of FIG. 2;

[0040] FIG. 4 is a right-side cross-sectional view of the vented bodily
fluid collection chamber of FIG. 3 showing an internal float member in an
open configuration;

[0041] FIG. 5 is a magnified cross-sectional view through a portion of the
volume limiting cerebrospinal fluid drainage system shown in FIG. 4 in
which details of a hinge and a seal plug located within the inflow port
during the time the float member is in the open configuration are more
clearly shown;

[0042] FIG. 6 is right-side cross-sectional view of a portion of the
vented bodily fluid collection chamber of FIG. 3 wherein the float member
located within the chamber is shown in the closed configuration with
buoyant force of the bodily fluid forcing the float member upward;

[0043] FIG. 7 is a magnified cross-sectional view through a portion of the
volume limiting cerebrospinal fluid drainage system shown in FIG. 6 in
which the seal plug is shown located between a chimney extension of the
float member and the hinge, and is within the inflow port to close the
inflow port against further fluid draining into the collection chamber;

[0044] FIG. 8 is an exploded perspective view of the float member and a
top member of the fluid collection chamber of the volume limiting
cerebrospinal fluid drainage system of FIG. 1 showing more details of the
hinge used to provide increased torsional stability to the float member;
and

[0045] FIG. 9 provides a cross-sectional view of another embodiment in
accordance with aspects of the invention in which a seal plug located on
a pivoting float member is used to seal a first vent port to limit the
flow of bodily fluid from a patient into the collection chamber; the
embodiment also shows a second vent port having a one-way valve to
provide a vent for air to flow into the chamber when the collected fluid
is to be drained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Referring now in more detail to the exemplary drawings for purposes
of illustrating embodiments of the invention, wherein like reference
numerals designate corresponding or like elements among the several
views, an embodiment of a body fluid drainage system for volume limited
drainage of a body fluid, such as cerebrospinal fluid (CSF), is
illustrated in FIGS. 1-8 in accordance with aspects of the present
invention.

[0047] Referring first to FIG. 1, one embodiment of the fluid drainage
system 100 of the present invention is adapted to drain cerebro-spinal
fluid (CSF) from the lumbar subarachnoid space of a patient. The drainage
system includes a catheter 102 adapted to be inserted into the lumbar
subarachnoid space through the low back of a patient to be treated. In
another embodiment, the catheter may be inserted into the lateral
ventricles of the patient to be treated to drain CSF from the brain. In
yet another embodiment, bodily fluids from other anatomical locations or
body cavities in a patient may be drained using the system. In one
embodiment, for example, accumulated fluid may be drained through the
catheter from the peritoneal cavity of a patient with ascites. The
drainage system further includes a flow limiting collection chamber 200,
and a drainage bag 104 having a drainage port 106. The collection chamber
and drainage bag are preferably vertically mounted on a pole 118, for
example an IV pole, positioned adjacent the patient to be treated.
Alternatively, the collection chamber and drainage bag may be vertically
mounted on the patient's hospital bed. The pressure at which CSF flows
into the collection chamber is determined by the height of the system in
relation to the patient. The rate of flow of CSF is controlled by the
volume of CSF flowing into the collection chamber and the timing of the
clinician periodically emptying the collection chamber. The rate of flow
of CSF is determined by the volume of CSF flowing into the chamber over
time, and the time periods between manual emptying of the collection
chamber by the clinician.

[0048] Referring also now to FIGS. 2-4, the collection chamber 200 has a
lumen 202 and is formed from a top member 210 connected with a bottom
member 220 by a wall 240. The wall may have indicia and/or markings 242
configured for indicating the volume of CSF contained within the
collection chamber. In one preferred embodiment, the wall is cylindrical
and transparent so that the clinician may view the contents of the
chamber and thereby accurately measure the amount of drained CSF in the
collection chamber. The volume of drained CSF in the collection chamber
200 may be seen and measured by the clinician using the volume markings
242 on the transparent wall 240 of the collection chamber. In one
embodiment, the volume markings may be spaced apart such that each volume
marking represents 10% of the total volume of the collection chamber
lumen 202. In another embodiment, the volume markings may be spaced apart
such that each volume marking represents 1 milliliter. A larger font may
be used for the volume markings at each 10 milliliters of volume. The
volume markings may be spaced further apart on the collection chamber
wall at volume levels where the collected fluid may contact the float
member 230, because the float member occupies some of the volume within
the collection chamber at such levels. Volume markings may also be
disposed on the drainage bag 104 (FIG. 1). The drainage bag may be
provided in a variety of sizes. In one embodiment the drainage bag is
configured to hold a volume of 1000 milliliters and is detachably
connected to the outflow tubing 114 so that such drainage bags can easily
be replaced when filled with drained fluid.

[0049] An inflow port 212 having a lumen is disposed in the top member. A
vent port 214 having a lumen is also included in the top member. The vent
port is connected with a vent chamber 204 that includes a filter 206. In
one embodiment, the filter is preferably hydrophobic and antimicrobial.
As used herein, "hydrophobic" is used to mean repelling water or
preventing the passage of liquid. "Antimicrobial" is used to mean
destructive to, or preventing the development of, or passage of,
microorganisms, or an agent that destroys or prevents the development of
microorganisms. However, the filter may simply be hydrophobic without
being antimicrobial in another embodiment.

[0050] The system is configured so that the volume of the vent chamber is
approximately 2 milliliters to 15 milliliters. This reduced volume, and
the hydrophobic filter provide an effective seal to CSF leakage, and
prevent drainage even if the system falls to the floor or the volume
limiting features described in more detail below are not capable of
functioning. An outflow port 222 having a lumen and configured for
draining CSF out of the collection chamber is disposed in the bottom
member. An inflow tubing 112 having a lumen is disposed between the
catheter 102 (FIG. 1) and the inflow port 212 for permitting the flow of
CSF into the collection chamber. An outflow tubing 114 having a lumen is
disposed between the outflow port 222 and the drainage bag 104. The
system 100 is thereby configured with a potential fluid flow path for CSF
from the patient to the drainage bag through the catheter, inflow tubing,
inflow port, collection chamber lumen, outflow port, and outflow tubing.

[0051] A valve 108 known in the art, such as a stopcock or a clamp, may be
disposed in the system to manually regulate the drainage of CSF, or to
provide an access site for sampling the CSF for laboratory examination.
Preferably, at least one valve 108 is positioned between the outflow
tubing 114 and the drainage bag 104 to allow for manual regulation of the
flow of CSF from the collection chamber 200 to the drainage bag. The
valve disposed between the collection chamber 200 and the drainage bag
may be manually opened to drain CSF into the drainage bag, for example,
after the clinician measures the volume of CSF in the collection chamber.
In at least one other embodiment, the outflow port 222 may, however, be
directly connected with the drainage bag by at least one stopcock,
thereby eliminating the need for the outflow tubing 114. Referring
briefly again to FIG. 1, at least one stopcock 110, or other type of
valve, may be positioned between the catheter 102 and inflow tubing 112,
for example to obtain samples of CSF from the patient, to shut off flow
to the collection chamber while the patient is transported, or if the
clinician wishes to exchange the collection chamber for a new one.

[0052] Referring again now to FIGS. 2-4, and also to FIGS. 5-7, the
collection chamber 200 further includes a buoyant float member 230 that
is pivotably connected with the top member 210 by a hinge 218. In at
least one embodiment, a float member lumen 231 is filled with air. In
other embodiments, the float member lumen may be filled with other gases,
or buoyant materials known in the art. A seal plug 232 is disposed on the
top of the float member adjacent the hinge. The seal plug includes a plug
head 236 and a plug support 234. In one embodiment, the plug head is
conical in configuration and the plug support is substantially
cylindrical, further including a fitting 235 for attaching the seal plug
to a hole in the float member. The seal plug head is configured to allow
flow into the chamber in an open configuration 250 and to seal an opening
213 in the inflow port 212 in a closed configuration 252. Flow of CSF
from the patient to the collection chamber through the inflow port to
fill the chamber is thereby prevented in the closed configuration. The
seal plug is further configured to disengage from the inflow port opening
and return to the open configuration when fluid in the collection chamber
is drained into the drainage bag 104. The seal plug and hinge are
discussed in more detail below.

[0053] In one preferred embodiment, the float member 230 includes a hollow
chimney extension 238 having a pressure equalization hole 239 at the top.
The pressure equalization hole communicates with air inside the float
member lumen 231. The pressure equalization hole permits gases under
pressure to flow into or out of the float member lumen 231 through the
pressure equalization hole. The pressure equalization hole prevents
pressure differences from developing between the inside and outside of
the float member during the sterilization process, thereby preventing
damage to the float member during sterilization under pressure. The
hollow chimney extension is advantageously configured to place the
equalization hole high up in the collection chamber 200 and well above
the collected fluid level, thereby preventing CSF from entering the float
member lumen. The diameter of the equalization hole may be minimized to a
size that allows movement of gases but inhibits movement of fluid through
the equalization hole. Fluid in the float chamber lumen is preferably
avoided because such fluid may affect buoyancy. In one embodiment, the
float member is formed by connecting a float member chamber 270 with a
float member bottom cap 268.

[0054] The present invention provides added patient safety by stopping
flow at a prescribed volume. Clinicians generally wish to drain patient
CSF in quantities between 10 milliliters and 50 milliliters per hour. At
least one embodiment includes a collection chamber 200 that provides for
a prescribed fluid drainage limit of 20 milliliters of fluid. At least
one other embodiment includes a collection chamber 200 that provides for
a prescribed fluid drainage limit of 30 milliliters of fluid. Still other
embodiments may limit drainage of fluid to volumes ranging from 10
milliliters to a larger quantity, such as 200 milliliters. In at least
one embodiment, the float member 230 occupies a volume of about 10
milliliters to about 15 milliliters. The collection chamber lumen 202 is
therefore preferably configured with a volume about equal to, or slightly
larger than the float member volume plus the prescribed volume. In one
embodiment, the volume of the collection chamber exceeds the combined
volumes of the float member and the prescribed volume by about two
milliliters to about ten milliliters.

[0055] When the collection chamber 200 is void of fluid, the float member
230 is configured to be in an open configuration 250 (FIGS. 4 and 5) that
permits flow of CSF through the inflow port 212 into the collection
chamber. In the open configuration, there is a gap 237 (FIG. 5) between
the seal plug head 236 and the inflow port, such that CSF can flow
through the inflow port opening 213 and into the collection chamber. When
the fluid in the collection chamber reaches the prescribed volume, the
buoyant float member is configured to lift towards the top member 210 and
pivot at the hinge 218 to a closed configuration 252 (FIGS. 6 and 7).
Referring specifically now to FIG. 7, in the closed configuration, the
plug head 236 has advanced into the inflow port opening, obliterating the
gap and sealing the inflow port 212, thereby substantially stopping the
flow of CSF from the patient to the collection chamber through the inflow
port.

[0056] In at least one embodiment, the gap 237 between the seal plug head
236 and the inflow port 212 opening 213 may be configured such that the
float member must pivot at the hinge 218 only a minimal amount from the
open configuration (FIGS. 4 and 5) to the closed configuration (FIGS. 6
and 7) to close the gap and stop the flow of CSF between the patient and
the collection chamber 200. A small gap is preferred to keep the seal
plug head aligned with the inflow port opening at all times. In at least
one preferred embodiment, the seal plug head has a conical shape, such
that the apex of the tip of the seal plug head is positioned slightly
within the inflow port opening in the open configuration (FIG. 5). The
seal plug head therefore needs to advance into the inflow port opening
only a small distance before the gap is closed and the seal plug head
seals flow through the inflow port opening. The seal plug head may,
however, be other shapes, for example spherical or oblong. In one
embodiment, the gap is closed when the hinge pivots less than five
degrees from the open configuration. In another embodiment, the gap is
closed when the hinge pivots less than ten degrees from the open
configuration. In still another embodiment, for example, the gap is
closed when the hinge pivots less than twenty degrees. The seal plug head
is preferably formed from a pliable yet resilient material such as
silicone. The seal plug is configured such that it releasably mates with
the inflow port to stop flow through the inflow port opening. The seal
plug head is configured to dislodge from the inflow port opening when
fluid is drained out of the collection chamber from the outflow port 222,
wherein the system is returned to the open configuration 250, and further
flow into the collection chamber is permitted. The seal plug is
elastically compliant to accommodate an accumulation of tolerances
between the float member and the inflow port that could produce a
misalignment between the seal plug and inflow port sufficient to prevent
said seal plug from fully closing the inflow port when the bodily fluid
has reached the predetermined level.

[0057] The seal plug 232 shown in FIGS. 4 through 9 has a conical head
236. As such, it is tapered along its length and therefore has multiple
varying diameters. Some of those diameters, such as at the apex, will fit
within the port with which the head 236 is paired and at least one
section of the head will have a diameter that is larger than the opening
of the port with which it is paired. Also, the seal plug may take forms
differing from the conical shape shown in the accompanying figures. As
one example, the seal plug may fit over the outside of the port as
opposed to fitting within the inside. Other configurations for a seal
plug are possible.

[0058] Referring also now to FIG. 8, in at least one embodiment, a hinge
218 includes a hinge arm 258 connected with the float member 230. In at
least one embodiment, the hinge arm is connected with the float member
generally adjacent the seal plug 232. Placement of the seal plug close to
the hinge is advantageous in keeping the head 236 of the seal plug
reliably aligned with the inflow port 212 opening 213. Placement of the
seal plug close to the hinge is also advantageous in maximizing leverage
forces of the seal plug into the inflow port opening. In one embodiment
shown in FIG. 8, the forces applied by the seal plug against the inflow
port are about three times the buoyancy forces applied upon the float
member by the prescribed volume of collected fluid.

[0059] In one preferred embodiment, the hinge 218 has a snap fit
configuration. Two hinge pins 260, having longitudinal axes coaxially
aligned with each other and with the center of rotation of the hinge, are
disposed at a distance from each other on the hinge arm 258. The hinge
further includes two hinge pin receiving members 262, which are disposed
on the top member 210 of the collection chamber 200. The hinge pin
receiving members are configured to receive the hinge pins to form the
pivotable hinge. The hinge pin receiving members may be connected with
the top member by hinge pin receiving member supports 264. When the hinge
pins are connected with the hinge pin receiving members to form the
hinge, the separation of the two hinge pins on the hinge arm is
advantageous in preventing torsional forces from misaligning the seal
plug and the inflow port 212 opening 213 during movement between the open
configuration 250 (FIGS. 4 and 5) and the closed configuration 252 (FIGS.
6 and 7). The fit of the hinge pins into the hinge pin receiving members
is configured to minimize friction between the hinge pins and the hinge
pin receiving members, thereby allowing relatively free pivotable motion
at the hinge. A snap fit hinge is advantageous in minimizing the costs of
manufacturing the system 100. Slots configured in the pin receiving
members may be provided to aid in snapping the hinge pins into the
receiving members.

[0060] Drainage rate into the collection chamber 200 is a function of time
and the height difference between the patient and the collection system,
for example the top member 210 of the fluid collection chamber. The rate,
volume, and pressures at which CSF flows from the patient to an empty
collection chamber are determined by the clinician. The collection
chamber may be aligned in relationship to bodily landmarks such as the
Foramen of Monro or the shoulder, or to the point of entry of the
drainage catheter into the patient. The present invention is advantageous
because the volume of CSF flowing from the patient to the collection
chamber 200 at the set position is automatically controlled and limited.
Complications resulting from overdrainage and/or overfilling of CSF are
at least reduced or are completely avoided. Furthermore, the present
invention frees the clinician from constant monitoring of the amount of
CSF drainage coming out of a patient while accurately measuring the
volume of CSF flow. The device 200 adds safety to the procedure of CSF
drainage by preventing overdrainage and/or overfilling from a poorly
positioned collection chamber. When properly used in an upright position,
the device may further prevent retrograde flow from the collection
chamber to the patient, thereby reducing the risk of CSF infection in the
patient.

[0061] Referring again to FIGS. 4 and 6, the system 100 includes a second
safety feature that prevents overdrainage and/or CSF leakage from the
system. That feature is an hydrophobic filter 206 that is included in a
vent chamber 204 that is connected with a vent port 214 disposed on the
top member of the fluid collection chamber. The hydrophobic filter is
advantageous in preventing contamination of sterile internal portions of
the system by microbes, and preventing leakage of CSF out of the system.
The system is configured so that the volume of the vent chamber is small,
for example, only approximately 2 milliliters to 15 milliliters. This
reduced volume, and the hydrophobic filter provide an effective seal to
CSF leakage, and prevent drainage of the CSF out of the chamber 200 even
if the system falls to the floor in a configuration where the float
member 230 is not capable of functioning to stop flow of CSF from the
patient. Such failure of the automatic shut off of CSF flow by the float
member 230 may occur due to stress, tilt, or damage. In at least one
embodiment, this system configuration provides an effective seal to CSF
leakage even in the event that the seal plug 232 fails to seal the inflow
port opening 213. The filter prevent the escape of CSF and the volume of
the vent chamber will accept no more than eighteen milliliters over the
prescribed volume of the collection chamber at a pressure of 122
centimeters of H2O. As mentioned previously, the filter 206 may also
include an antimicrobial agent.

[0062] Repeated contact of an antimicrobial filter 206 with CSF may
degrade the filter, for example by clogging the filter, or may allow
microbes to cross the filter. The system 100 is advantageously configured
such that, if the collection chamber 200 is mounted generally vertically,
the float member 230 and seal plug 232 will seal off flow between the
collection chamber 200 and the inflow port 212 before draining fluid
reaches the filter. In one embodiment, the system will prevent drained
fluid from contacting the filter if the collection chamber is mounted at
an angle of 10 degrees or less from vertical in two axes at 50
centimeters of H2O. In at least another embodiment, the system will
seal the collection chamber at pressures less than 122 centimeters of
H2O, before fluid reaches the filter.

[0063] The system 100 is useful for providing controlled external drainage
and monitoring of CSF from the brain or lumbar spine subarachnoid space.
The system may also be used for sampling CSF, providing temporary sterile
external drainage of CSF, and/or for monitoring of ICP with the
connection of a pressure transducer to the stopcock 108 connected with
the catheter 102. In at least one embodiment, connections between the
catheter 102 and tubings 112, 114 may be made using stopcocks, and/or
Luer lock connections 110, and or other connectors known in the art. The
system may further include access ports or sites, for example needle free
access ports known in the art.

[0064] Referring again to FIGS. 1-3, the system preferably includes
support members known in the art such as pole clamps 120 or rope
attachment members 132 (FIG. 8) for mounting the system to an IV pole 118
or the patients bed. The system may further include a support member 224
for retaining the drainage bag 104 to the collection chamber 200. The
support member 224 may include a stopcock support 226 for a stopcock 108,
and a drainage bag support 228. The collection chamber may further
include at least one clip 216 for retaining the inflow line 112.

[0065] The system may be made from compatible materials known in the art
such as plastics, PTFE, and silicone. In one embodiment, the device
includes latex free materials. The materials forming the device should
preferably be compatible with medical sterilization systems, for example
ethylene oxide gas sterilization or radiation sterilization. The system
may be formed by connecting together the various portions using snap
fittings, adhesives, heat, screws, rivets, sonic welding or other
connection techniques known in the art.

[0066] In an embodiment of a method in accordance with aspects of the
invention, bodily fluid is received in a collection chamber through an
inflow port disposed in the top of the container. As the chamber
accumulates the received fluid, the fluid applies an upward buoyant force
to a float member pivotally mounted at the top of the container with a
hinge. In response to the upward buoyant force, the float member pivots
upward about the hinge. At a certain volume of fluid accumulated in the
chamber, the float member closes the inflow port thereby stopping flow of
fluid into the chamber. The method thus includes the steps of moving the
float between a closed configuration, in which fluid is prevented from
flowing into the chamber, to an open configuration in which fluid may
flow or drain into the collection chamber.

[0067] The method also vents the chamber as bodily fluid is received. In
one aspect, the step of venting includes preventing the passage in or out
of the chamber of liquid through means of an hydrophobic filter. In
another aspect the venting step includes passing vented fluid past an
anti-microbial agent.

[0068] In other aspects, the method includes closing the inflow port with
a seal plug having a tip or apex that is continually within the inflow
port during both the closed configuration and the open configuration. The
mounting of the pivoting float member may be performed by a hinge having
a hinge arm and hinge pins that are selected to limit torsional motion of
the float member so that the float pivots in only one plane. By selecting
the relative sizes of the chamber and float, the angle of movement of the
float during pivoting motion can also be limited.

[0069] Turning now to FIG. 9, another embodiment is shown. As with the
previous embodiment described above, this embodiment also limits the
volume of bodily fluids drained from a patient. Rather than directly
plugging the inflow port 212 to limit flow as was shown and described in
the previous embodiment, this embodiment limits fluid from entering and
filling the collection chamber 300 by using the seal plug 232 disposed on
a pivoting float member 330 to seal a first vent port 332 of the
collection chamber once the chamber has filled sufficiently. In this way,
bodily fluid from the patient is allowed to flow into the collection
chamber to displace air, which flows out the first vent port. As the
inflow of bodily fluid proceeds to fill the collection chamber, the float
member pivots or rotates in response to the bodily fluid until the seal
plug 232 mounted to the float member seals the first vent. Sealing the
first vent prevents the further displacement of air in the collection
chamber and as a result, the pressure in the collection chamber will
equal the patient fluid pressure and flow of the patient's bodily fluid
into the collection chamber will cease. The first vent includes a first
filter 334 that may be the same as described above in relation to the
filter 206 of the first embodiment.

[0070] The process of collecting bodily fluid in this embodiment is
similar to that of the previous embodiment. The outflow port (not shown)
of the collection chamber is closed, in this embodiment by closing a
stopcock 108 located on an outflow tube 114 from the chamber (see FIG.
1), although other means for closing the outflow port may be devised. The
inflow port 212 of the chamber is opened, in this embodiment, by opening
a stopcock 116 located on an inflow tube 112 between the patient and the
chamber (see FIG. 1).

[0071] To drain the bodily fluid collected in the collection chamber 300,
air must be allowed to enter the chamber to displace the fluid drained.
Because the inflow port is closed by means of an upstream clamp or
stopcock 116 in this case (see FIG. 1) and the first vent 332 is sealed
by the seal plug 232 as shown in FIG. 9, fluid cannot enter the
collection chamber through these two paths and drainage is severely
restricted or prevented. To provide another path for air to enter the
collection chamber to displace bodily fluid draining from the collection
chamber, a second vent port 340 is provided in the top member 342. In
this embodiment, a one-way valve (check valve) 344 with a low cracking
pressure is disposed in the second vent. The one-way valve is disposed in
the second vent to permit the inflow of air from the surrounding
atmosphere into the collection chamber through the second vent when the
cracking pressure is experienced and the one-way valve opens but will not
permit the outflow of either liquid or gas from the collection chamber
through the second vent. The second vent also includes a second filter
346 that functions in the same way as the filter 334 in the first vent
332 functions, and may therefore be formed of the same materials. The
one-way valve referenced above may take various forms well known to those
skilled in the art and consequently, no further details are provided
herein.

[0072] To drain collected bodily fluid from the collection vessel 300 in
the embodiment of FIG. 9, the flow inlet 212 is closed, through closing
the inlet stopcock 116 (FIG. 1) in this embodiment. The flow outlet 222
is opened, through opening the drain stopcock 108 (FIG. 1) in this
embodiment. It is to be noted that arrangements and devices other than
the upstream and downstream stopcocks shown and described here may be
devised to achieve the same effects. As gravity pulls on or applies
outflow pressure on the fluid in the collection chamber 300 to tend to
cause it drain out of the chamber, the air pressure in the chamber will
reduce below atmospheric pressure thereby creating a pressure
differential across the one-way valve 344 disposed in the second vent.
When this pressure differential becomes large enough so that it equals
the one-way valve's cracking pressure, the one-way valve will open to
allow air from the surrounding atmosphere to flow into the collection
chamber to replace the out-flowing collection chamber fluid, thereby
enabling drainage of the chamber. As the collection chamber drains, the
float member 330 will pivot downwards thereby opening the first vent 332
rendering the collection chamber once again ready to collect further
patient bodily fluid once the upstream stopcock 116 is opened.

[0073] To stop the out-flow of fluid from the collection chamber 300 and
resume collection of the patient's bodily fluid, the outflow port 222
(not shown) is closed and the inflow port 212 is opened. In this
embodiment, the foregoing is effected by closing the drain stopcock 108
and opening the fluid inlet stopcock 116 (FIG. 1). It will be noted that
the top member 342 of the collection chamber 300 in this embodiment has
been modified from that in the first embodiment. In the present
embodiment, the top member includes the same inflow port 212 as the first
embodiment but at a different location, as will be discussed in more
detail below. Two vent ports are provided, i.e., a first vent port 332
through which air flows out of the collection chamber and a second vent
port 340 through which air may flow into the collection chamber. Both
include filters 334 and 346 but the second vent port also includes a
one-way valve 334 as described above.

[0074] The embodiment of FIG. 9 also illustrates a modified float design
330 that facilitates visualization of the flow of bodily fluid into the
collection chamber 300 and the amount of fluid remaining The side wall
240 in this collection chamber is also transparent and although not
shown, may include various types of indicia to visually indicate to the
observer the quantity of bodily fluid collected. In addition, the inflow
port 212 includes a drop former 350 so that drops 352 of bodily fluid are
formed as the fluid flows into the collection chamber. In accordance with
a feature of this embodiment, the top member 342 and the float 330 are
specifically designed in relation to each other so that the inflow port
212 and the drops of bodily fluid being collected from the patient are
more clearly visible to an observer. In the embodiment shown in FIG. 9,
the inflow port is located on the opposite side of the collection chamber
from the hinge 218 used to mount the float member 330. Additionally, the
float member has a smaller size than that of the float member 230 in
FIGS. 2 through 8 so that it does not extend to a position under the
inflow port. Therefore, the path 354 of the drops 352 of bodily fluid
entering the collection chamber from the inflow port to accumulate and
fill the chamber are not blocked from view by the float member 330 and
are more easily seen by an observer.

[0075] It will be noted that the float member 330 in the embodiment of
FIG. 9 includes the same chimney extension 238 with a pressure
equalization hole 239 and may be filled with air or other substance
contributing to the buoyancy of the float member as in the previous float
member and as previously discussed. Additionally, the seal plug 232 and
the hinge 218 are mounted to the float member 330 and function in the
same manner as those devices in the previous float member 230.

[0076] Thus there has been shown and described a body fluid drainage
system including a mechanical volumetrically controlled shut off device.
The shut off device automatically shuts off flow of fluid when a desired
volume of drained fluid is reached and automatically opens up again,
permitting further flow, when the user drains the fluid out of the shut
off device. One embodiment of the present invention provides for volume
limited drainage of cerebro-spinal fluid (CSF). The system provides for
volume limited CSF drainage from the brain or from the spine. Also show
and described is a method for volumetrically controlled drainage of CSF
using the body fluid drainage system described herein.

[0077] The invention may be embodied in other forms without departure from
the spirit and essential characteristics thereof. The embodiments
described therefore are to be considered in all respects as illustrative
and not restrictive. Although the present invention has been described in
terms of certain preferred embodiments, other embodiments that are
apparent to those of ordinary skill in the art are also within the scope
of the invention. Accordingly, the scope of the invention is intended to
be defined only by reference to the appended claims.

Patent applications by Brian Hoffman, Princeton, NJ US

Patent applications by Eric Scott Clasen, Hillsborough, NJ US

Patent applications by Michael Mcdermott, San Francisco, CA US

Patent applications by William R. Chang, Colonia, NJ US

Patent applications by INTEGRA LIFESCIENCES CORPORATION

Patent applications in class Receptacle attached to or inserted within body to receive discharge therefrom

Patent applications in all subclasses Receptacle attached to or inserted within body to receive discharge therefrom